"BGK" (reversible, element, unlabeled) transform of 1,3,5,7,...

Terms

a(0) =1a(1) =1a(2) =3a(3) =8a(4) =15a(5) =40a(6) =99a(7) =236a(8) =646a(9) =1584a(10) =4081a(11) =10349a(12) =25912a(13) =64722a(14) =160286a(15) =397687a(16) =966020a(17) =2371653a(18) =5743454a(19) =13810783a(20) =33249279a(21) =79400369a(22) =188904792a(23) =446408824a(24) =1054545693a(25) =2475898367a(26) =5787434089a(27) =13484174982